DIMENSIONS

where name is arbitrary and alist is a 1- or 2-dimensional array.
This function returns the dimensions list of the array alist. That
list will either be of the form (dim1) or (dim1 dim2), depending on
whether alist is a 1- or 2-dimensional array. Dim1 and dim2 will be
integers and each exceed by 1 the maximum legal corresponding index.
Thus, if dimensions returns, say, '(100) for an array a
named 'delta1, then (aref1 'delta1 a 99) is legal but
(aref1 'delta1 a 100) violates the guards on aref1.
Dimensions operates in virtually constant time if alist is the
semantic value of name. See arrays.